But the MetService says cooler days are on the horizon.
MetService meteorologist Lisa Murray said a cold front moving up New Zealand would bring lower temperatures today, with a few cooler days to come.
Temperatures reached 20.7C in Tauranga on Tuesday and 20.1C yesterday. The Kaimai Ranges saw temperatures reach between 15C and 16C.
Today's temperatures for Tauranga were expected to reach 18C, dropping to 17C tomorrow and over the weekend.
The coldest temperatures for the week would probably be tonight, about 6C, she said.
"There is quite a cold southwesterly coming through," Ms Murray said.
"When it came over Dunedin it dropped from 21C down to 11C, so it's quite a cold air mass.
"It won't be so dramatic by the time it gets up to Tauranga."
A bit of cloud was due to come in last night and there could be brief morning showers today as the westerlies changed to a fresher southwesterly.
Friday, Saturday, Sunday and Monday would be mainly fine with temperatures in the late teens.
Niwa forecaster Chris Brandolino said the recent spring weather was on par with previous years but would intensify. Niwa was now 99 per cent certain that El Nino conditions would continue for at least the next three months.
He said the current event was tracking close to the 1997/1998 El Nino - the strongest since 1950 - and was expected to intensify between January and March.
Above-normal pressures were expected for the north and west of New Zealand until December, while below-normal pressure was expected for the east and south of the country.
- Additional reporting Sandra Conchie